With the introduction of notebook computers and other portable devices utilizing battery power, electronic circuits in the device are required to utilize as little power as possible to preserve the batteries for an extended period of time. Even with devices that are not battery powered it is desirable to have electronic circuits that operate with as little power consumption as possible to conserve energy. Direct current (DC) power consumption in electronic devices can be approximated by the equation P=VI whereas alternating current (AC) power consumption can be approximated by the equation CV.sup.2 F. Thus power consumption is proportional to the voltage supply V or the square of the voltage supply V.sup.2. In either case, power consumption can be decreased by lowering the voltage power supply. For example, the decrease in DC supply voltage from 5.0 volts to 3.3 volts will approximately decrease power consumption by over forty percent. With the increase of portable electronic and battery operated devices the power consumption and operational time of the portable units has become important. Although most electronic components currently utilize 5.0 volt and 3.3 volt component technology, the trend is toward developing electronic components that operate at a voltage of lower than 3.3 volts. The development and implementation of process technology based on a voltage of less than 3.3 volts promises significant power savings in future systems.
Many electronic components used by the typical consumer require the use of some form of electronic data storage. For example, consumer devices such as handheld PCs, digital cameras, audio recorders, smart cellular phones, etc., require a small form factor data storage media, and a convenient method for transporting data to a PC or other electronic device for manipulation or enhancement. Small form factor expansion memory cards supporting a variety of technologies (e.g. Flash, Read-Only-Memory ("ROM"), One-Time Programmable Read-Only Memory ("OTPROM"), Electrically Erasable Programmable Read-Only Memory ("EEPROM"), Dynamic Random Access Memory ("DRAM") and Static Random Access Memory ("SRAM")) have been developed to support the electronic transfer of data from one electronic device to another. In order to facilitate the movement towards reducing the power consumption of portable electronic components, it is desirable to provide memory cards that are compatible with a system voltage of less than 3.3 volts. It is important to note, however, that in some instances it may be desirable or necessary to use a memory card that is capable of operating at one or more voltages. In any event, it is necessary to provide a memory card that is compatible with the supply voltage provided by a single voltage or multivoltage host system.
Since a host device and/or memory card may be designed to operate at 5.0 volts, 3.3 volts, at a voltage of less than 3.3 volts, or any voltage combination thereof, it is desirable to provide a connection system that will accommodate the electrical connection between such components. Mismatching the power supply of a memory card with that of a host device can cause damage to data stored in the memory card and may result in damage to the memory card itself.
Many prior art memory cards utilize voltage detection circuits that inhibit the operation of a memory card when the memory card operating voltage is incompatible with the host device supply voltage. Although the use of a voltage detection circuit is useful in preventing damage to data stored in a memory card, the voltage detection circuit does not prevent the insertion of a memory card into an incompatible host. Because many portable electronic devices are used by consumers who are typically unaware of the particular operating voltage of the devices they operate, the ability to physically connect a memory card and host device having incompatible voltages can be problematic. For instance, the user of a digital camera who is hoping to capture the birth of a child may be particularly unforgiving when he or she discovers that the image was not recorded because the memory card operating voltage was incompatible with the host device supply voltage.